Show model override immediately in Agent Tree visualization

When a model override is specified via the control session, the Model
Selector node now displays the requested model immediately instead of
showing "Selecting optimal model..." until completion. This gives better
visibility into which model is being used for each mission.

src/agents/orchestrator/root.rs

@@ -741,11 +741,19 @@ impl Agent for RootAgent {
         }
 
         // Simple task: add remaining nodes
-        root_tree.add_child(
+        // Check if there's a model override - show it immediately on the node
+        let requested_model = task.analysis().requested_model.clone();
+        let model_selector_node = if let Some(ref model) = requested_model {
+            AgentTreeNode::new("model-selector", "ModelSelector", "Model Selector", &format!("Using: {}", model))
+                .with_budget(10, 0)
+                .with_status("running")
+                .with_model(model)
+        } else {
             AgentTreeNode::new("model-selector", "ModelSelector", "Model Selector", "Selecting optimal model")
                 .with_budget(10, 0)
                 .with_status("running")
-        );
+        };
+        root_tree.add_child(model_selector_node);
         ctx.emit_tree(root_tree.clone());
 
         ctx.emit_phase("selecting_model", Some("Choosing optimal model..."), Some("RootAgent"));
@@ -782,10 +790,11 @@ impl Agent for RootAgent {
             default_model
         };
 
-        // Update model selector node
+        // Update model selector node with final selected model
         if let Some(node) = root_tree.children.iter_mut().find(|n| n.id == "model-selector") {
             node.status = "completed".to_string();
-            node.selected_model = Some(selected_model);
+            node.selected_model = Some(selected_model.clone());
+            node.description = format!("Using: {}", selected_model);
             node.budget_spent = 3;
         }
 

src/api/control.rs

@@ -394,7 +394,11 @@ pub async fn post_message(
     state
         .control
         .cmd_tx
-        .send(ControlCommand::UserMessage { id, content, model: req.model })
+        .send(ControlCommand::UserMessage {
+            id,
+            content,
+            model: req.model,
+        })
         .await
         .map_err(|_| {
             (